The present invention relates generally to the field of digital communications. More particularly, the present invention relates to transmission of digital data via power transmission and distribution lines.
The use of power lines as a communication medium is well known, dating back to efforts in the 1930""s to provide telephone communication to rural areas. More recently, systems have been devised that utilize the power line as a medium to communicate data between computers. Some attempts have been made to use these systems to provide Internet access. To date traditional modulation schemes such as Frequency Shift Keying (FSK), Direct Sequence Spread Spectrum (DSSS), and Orthogonal Frequency Division Multiplexing (OFDM) have been used.
The use of chirped frequency shift keying for transmission of digital data over power lines has been proposed. For further details, refer to U.S. Pat. No. 4,468,792 to Baker et al.
The use of spread spectrum techniques for transmission of digital data via power lines has also been proposed. For further details, refer to U.S. Pat. No. 5,375,141 to Takahashi, as well as a number of patents to Sutterlin et al.: U.S. Pat. No. 5,937,003, U.S. Pat. No. 5,748,671, U.S. Pat. No. 5,579,335, and U.S. Pat. No. 5,461,629. U.S. Pat. No. 5,359,625 to Vander Mey et al. teaches the use of spread spectrum in noisy networks, such as RF channels and AC power lines.
All of these traditional modulation schemes utilize a sinusoid wave as a center carrier, and vary the amplitude and/or frequency and/or phase of that carrier so as to convey the information to be communicated.
Systems that use conventional modulation schemes for power line communications have issues such as radiated emissions, reflections, security and interference from other sources, and channel capacity.
Thus, what is needed is a way to transmit data via power lines while mitigating the above-noted problems of radiated emissions, reflections, security and interference from other sources, and channel capacity.
The present invention does not use sine waves as a carrier wave at all. Instead, bipolar Gaussian pulses are used to communicate data over standard power lines.
It is an object of the present invention to provide a signaling scheme for use in transmission of data via power lines.
It is another object of the present invention to provide a system for use in transmission of data via power lines.
It is yet another object of the present invention to provide a system for power line data transmission that minimizes radiated power.
It is still another object of the present invention to provide a system for power line data transmission that has secure transmission of data.
It is a further object of the present invention to provide a system for power line data transmission that has spectral smoothing characteristics.
It is an additional object of the present invention to provide a system for power line data transmission that makes each channel resistant to interference.
It is another object of the present invention to provide a system for power line data transmission that modulates pulses in a train of bipolar Gaussian pulses according to time position and amplitude of the pulses.
Additional objects and advantages of the present invention will be apparent in the following detailed description read in conjunction with the accompanying drawing figures.